[jira] [Created] (ARROW-8875) [C++] use AWS SDK SetResponseStreamFactory to avoid a copy of bytes

["Remi Dettai (Jira)" <ji...@apache.org>]

Remi Dettai created ARROW-8875:
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             Summary: [C++] use AWS SDK SetResponseStreamFactory to avoid a copy of bytes
                 Key: ARROW-8875
                 URL: https://issues.apache.org/jira/browse/ARROW-8875
             Project: Apache Arrow
          Issue Type: Improvement
          Components: C++
            Reporter: Remi Dettai


Currently, in `GetObjectRange` of f3fs the `GetObjectRequest` has no `ResponseStreamFactory` assigned. This means that the bytes returned by the S3 API are first sent to a `std::basic_stringbuf`. To my understanding this has two performance impacts:
 * `std::basic_stringbuf` uses a growing array to buffer the response, so lots of allocations here
 * on top of that, you have a copy operation from the `std::basic_stringbuf` when data is read into the Arrow buffer.

This seems to be a bit costly.

With `ResponseStreamFactory`, we might manage to get the data directly into the Arrow buffer.

I can take a try at it, but I would need some advice. Is there an existing utility to stream data into an Arrow buffer (if it exists, it is well hidden!) ? or should I stream the data into a plain array and then transfer ownership to Arrow ?



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